Liquid propulsion apparatus and method of fabrication

ABSTRACT

An improved liquid pumping unit for marine propulsion and the like includes as the rotatable shaft of an internal combustion engine a conduit which includes internal impeller vanes for pumping liquid therethrough at high volume and velocity and which also serves as the flywheel of the engine.

United StatesPatent [191 Smith LIQUID PROPULSION APPARATUS AND METHOD OF FABRICATION Albert C. Smith, Box 782, Los Altos, Calif. 94022 Filed: Sept. 23, 1971 Appl. No.: 184,462

Inventor:

US. Cl 115/16, 60/221, 417/355, 418/61 Int. Cl B6311 25/46 Field of Search 60/221; 418/61; 7 115/16; 417/364, 355

References Cited UNITED STATES PATENTS 12/1969 Anthoney 60/221 Jail. 15, 1974 Primary Examiner-Duane A. Reger Assistant Examiner-Jesus D. Sotela A ttorney-Albert C. Smith [57] ABSTRACT 15 Claims, 4 Drawing Figures PATENIEDJ SQM v 3.785.327

SHEET 1 0F 3 c; 2] 48 42 27 25 33 :&

15 23 17 29 pp 35 17 19 H l B 41 l igure 1 INVENTOR ALBERT C. SMITH INVENTOR ALBERT C. SMITH LIQUID PROPULSION APPARATUS AND METHOD OF FABRICATION BACKGROUND OF THE INVENTION Modern marine propulsion units commonly include a prime mover such as an internal combustion engine which is mechanically coupled to an external propeller. For pleasure crafts, the external propeller is either part of an outboard drive unit mounted astern of the boat or is mounted beneath the boat near the stern. Propellers or drive units mounted and operated in these conventional exposed configurations commonly require such elaborate coupling mechanisms as gear trains, transmissions, clutches, and the like and are subjct to damage upon contact with floating debris or rocks. Also, these exposed propeller configurations constitute a major safety hazard to swimmers in water-contact sports such as water skiing where the boat must be operated in close proximity to a swimmer.

In recent years, high-volume water pumps mounted in pleasure crafts to discharge water astern at high velocities have gained wide acceptance as safe and efficient marine propulsion units. In these units, the prime mover (e.g., gasoline engine) is coupled to an axialflow impeller pump and the entire unit is mounted inboard toward the stern of the boat. A water inlet disposed flush with the bottom of the boat near the stern picks up water which is then pumped through the unit and discharged astern to provide reaction propulsion in the steerable direction of discharge of the jet stream of water. A thrust reverser which deflects the discharge stream of water downwardly and under the boat toward the bow provides reverse maneuverability. Units of this type are described in the literature (see, for example, U.S. Pat. No. 3,030,909 issued on Apr. 24, 1962 to R. H. Barnes et al). One disadvantage encountered in propulsion units of this type is that the combined length of the engine and propulsion pump takes up a substantial amount of space toward the rear of the boat. Also, the use of a conventional engine with the added weight of the coupling shaft, flywheel and lengthy mounting brackets decreases the resulting thrust-to-weight ration with concomitant degradation in acceleration and performance of the boat.

SUMMARY OF THE INVENTION In accordance with the preferred embodiment of the present invention, an axial-flow impeller pump is formed within a rotatable conduit which constitutes the output shaft of an internal combustion engine. This reduces the over-all length and weight of the propulsion unit, eliminates substantially all external rotating ele ments and requires only simple plumbing connections of the water inlet and discharge nozzle at opposite ends of the impeller-output shaft. Also, the distribution of metal about the periphery of the large-bore, impelleroutput shaft has sufficiently high moment of inertia to serve as a flywheel for the engine, thereby further decreasing the over-all weight of the propulsion unit.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial sectional view of the propulsion unit according to the present invention mounted near the stern of a boat;

FIG. 2 is a lateral sectional view of a rotor-type piston stage and an output shaft-impeller tube in an internal combustion engine according to the present invention;

FIG. 3 is a partial longitudinal sectional view of the propulsion unit showing the operating elements of the propulsion unit; and

FIG. 4 is a sectional view showing a rotor-type piston stage geared to an output shaft-impeller tube in an internal combustion engine according to one embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. I, there is shown a partial sectional view of the marine propulsion unit according to the present invention. The unit 7 is shown disposed within a hull 9 of a boat near the stern thereof with only water inlet 11 and outlet 13 connections attached to the propulsion unit 7. The propulsion unit 7 includes a reciprocating internal combustion engine, preferably of the rotary engine type, having a hollow impeller-output shaft 15 arranged within the unit 7 to form a liquid conduit from the inlet 11 to the outlet 13. The impelleroutput shaft 15 includes one or more stages of turbinelike impeller vanes 17 disposed within the internal conduit of the impeller-output shaft. Eccentric cam lobes 19 carried on the impeller-output shaft 15 provide the reciprocating crank means associated with an internal combustion engine. One or more such eccentric cam lobes 19 may be formed on the impeller-output shaft 15, depending upon the horsepower output desired from the propulsion unit 7. With the eccentric cam lobes 19 thus disposed on the shaft, the internal conduit through the impeller-output shaft 15 is preserved uniformly smooth in a continuous axial bore from the inlet end to the outlet end. Also, a power takeoff shaft 21 may be orthogonally oriented with respect to the impeller-output shaft 15 intermediate a pair of eccentric cam lobes 19. This power takeoff shaft may be coupled to the impeller-output shaft 15 through helical gearing means of conventional design to serve as the power shaft for such accessory items (not shown) as oil pump, water circulator, generator, and starter.

The impeller-output shaft 15 is rotatably mounted in main bearings 23, 25 disposed at each of the ends thereof and additionally may also be supported intermediate the ends by additional main bearings disposed along the length of the shaft 15. One or more of these bearings may be a thrust bearing designed to transfer to the stationary portion of the engine (and, hence, to theboat 9) the reaction thrust imparted to the impeller-output shaft 15 as the propulsion stream of water is discharged rearwardly. Seals 27 and 29 are disposed adjacent the main bearings 23, 25 near the ends of the shaft 15 to exclude water from the main bearings and other internal parts of the propulsion unit 7.

The impeller-output shaft 15 thus disposed within the propulsion unit 7 contains substantially its entire mass at an average typical radius of a few inches from the axis of rotation and along the entire length of approximately 2 feet. The moment of inertia of this impelleroutput shaft 15 may thus be made adequate to serve as an integral flywheel for the smooth, continuous operation of the internal combustion engine. The need for an additional flywheel with concomitant weight and acceleration problems is thus eliminated, thereby lightening the over-all weight and enhancing the over-all performance of the present propulsion unit. With the exception of the power takoff shaft 21, there is substantially no rotating machinery exposed outside of the propulsion unit. However, no mechanical output couplings, shafts, clutches, transmissions, or the like, need be attached to the propulsion unit 7 for the purpose of propelling the boat 9; the only connections required being the inlet and outlet water connections 11 and 13.

The inlet 11 includes a conduit which may be flangefitted to the end of the propulsion unit 7 in substantial axial alignment with the internal bore of the water conduit through the impeller-output shaft 15. This inlet 11 includes a through-hull connection 39 disposed to pick up water during the general forward movement of the boat. The inlet 11 may be screened on the outside of the hull bottom 10 by a suitable protective grill or guard 37. There are thus no external mechanical couplings or elements of rotating machinery exposed outside the hull 9 of the boat.

The inlet 11 also includes an actuatable flapper valve 35 which may be disposed across the conduit through the inlet in order to shut off water flow into the propulsion unit 7. In the retracted position (as shown), the flow of propulsion water through the inlet 11 to the propulsion unit 7 is unimpeded and thus provides the requisite forward thrust. With the flapper valve 35 disposed in the alternate position across the inlet conduit as shown, the flow of water to the propulsion unit 7 is impeded such that insufficient forward thrust can be developed, thus providing neutral" operation of the propulsion unit 7 while the engine continues running. An auxiliary water connection 33 to the inlet conduit for channeling cooling water to the water circulator (not shown) of the propulsion unit 7 is connected on the forward side of. the flapper valve 35 in order to assure an adequate flow of cooling water to the propulsion unit 7 during all phases of operation (i.e., forward, neutral and reverse) of the propulsion unit 7.

The outlet 13 includes a manually directable nozzle 41 which is rotatable about a substantially vertical axis to provide steerage by diverting the discharge stream of water under pressure in the desired direction. This nozzle 41 may be attached to conventional steering means through a suitable control arm 43 and associated steering mechanism 45. In addition, a thrust reverser 47 is mounted on the nozzle 41 for pivotal movement thereon about a substantially horizontal axis. In its normally inactive upright position, the thrust reverser 42 is disposed out of the discharge stream of water and thus has no effect. However, when the thrust reverser 42 is disposed in its down position, as shown, a substantial part of the discharged stream of water is deflected downwardly and forwardly of the boat 9 in order to provide reverse maneuverability. This obviates the need for conventional gear change mechanisms to provide reverse maneuverability.

The outlet 13 includes an integral exhaust port 48 which receives the exhaust gases present in the manifold passage 47 of the propulsion unit 7 and serves to introduce these exhaust gases into the discharged stream of water in a manner typically associated with a Venturi constriction. In this way, exhaust gases and cooling water released into the exhuast manifold passage 47 are introduced into the discharged stream of water in such a manner that the gases and cooling water are carried away in high-velocity propulsion streams of water. This aids in reducing operating noise during forward movement and also assures substantially clean performance of the marine propulsion unit. By selectively providing controlled amounts of leakage of water through the flapper valve 35 during neutral" operation, a sufficient flow of water through the impelleroutput shaft 15 of the propulsion unit 7 may be maintained in order to muffle exhaust noises and gases being discharged through the outlet 13 but without sufficient velocity or volume to introduce any substantial forward thrust.

Referring now to FIG. 2, there is shown a simplified sectional view of one rotor stage of a rotary engine according to a preferred embodiment of the marine propulsion unit of the present invention. The engine includes a conventional epitrochoidally-shaped combustion chamber with a generally triangular-shaped rotor disposed to rotate and reciprocate therewithin on an eccentric cam lobe 19 carried by the impeller-output shaft 15. The generally triangular rotor 53 with its chamber seals and oil seals 55, 57 is rotatably mounted on the eccentric cam lobe 19 by means ofa roller bearing 59, or the like. The hollow impeller-crankshaft 15 includes a plurality of impeller vanes 17 disposed substantially radially inwardly from the internal walls of the impeller-output shaft 15. This impeller-output shaft 15 also includes one or more oil passages 61 disposed within the shell of the shaft to provide oil under pressure to the main bearings and to the rotor bearings 59, as later described herein. The inlet port to the chamber 51 may be coupled in common to one or more rotor chambers and also to a conventional carburetor and air intake 46 for suitable administration of the mixture of fuel and air required for proper operation of an internal combustion engine. The exhaust port 63 may be coupled to one or more rotor chambers and is also coupled to the manifold passage 47 which communicates with the passage 48 (of partial circumferencial form) in the outlet 13. This passage may be formed within the outlet 13 by a baffle rib cast within the outlet 13 to serve as an intermediate partition between the exhaust gases and the discharged water stream about the circumference, or part thereof, of the discharged water stream. At the end of the passage 48, the exhaust gases are then introduced into the discharged water stream to muffle the exhaust noises and carry away the exhaust gases in the high-velocity discharge stream of water. Additionally, the baffle rib 75 may include a resiliently-biased flapper valve 79 which is disposed within the inlet 13 to act as a one-way baffle for preventing the backflow of water into the exhaust manifold passage 47 due, for example, to reverse flow of water into the outlet 13 caused by a following sea, or the like. Additionally, a supply of cooling water which may be circulated through the cooling passages 81 about the combustion chambers of the propulsion unit 7 may also be discharged into the exhaust passage 47 in a conventional manner in order to maintain the operating temperature of the exhaust manifold at a safe, low temperature during continuous operation.

Referring now to FIG. 3, there is shown a pair of rotor stages in a rotary-combustion engine configuration. Each of these chambers includes a rotor of generally triangular shape 53 mounted via bearings 59 on an eccentric cam lobe 19, as shown in FIG. 2. A central main bearing 71 may be disposed within the unit 7 between the rotor stages and may include an annular groove of sufficient recess to receive the power takeoff shaft 21 and mating helical gears carried on shafts 21 and 15. The gear on shaft 21 engages a helical gear 73 carried by the impeller-output shaft 15 to serve as the means by which the impeller-output shaft is rotated in starting the engine and as the means by which such accessory units as an oil pump, a water circulating pump, and a generator are driven during operation of the engine. An oil pump (not shown) of conventional design may be arranged to pick up oil in the oil sump of the engine and to discharge the oil under pressure into the annular groove, thereby to supply oil under pressure to the oil passages 61 which communicate with both the annular groove in the auxiliary bearing 71 and with the rotor bearings 59 and main bearings 23, 25. The impeller-output shaft 15 with its axial bore, impeller vanes 17, gears 73, cam lobes 19 and oil passages 61 may be formed in half sections and then joined along longitudinal seams. For example, each half sec tion may be forged to generally semicylindrical, hollow shape with portions of the cam lobes integrally attached thereto. Also, one or more stages of impeller vanes may be forged or welded into position and suitably machined to shape prior to assembly of mating half sections. In addition, the oil passages 61 may be formed as recessed channels in at least one of the mating faces of the half sections. The half sections may then be welded together along longitudinal seams (on internal and external surfaces) and be machined to final dimensions in the critical areas of the cam lobes 19, bearing and seal areas, gears 73, and the like. The impeller-output shaft 15 thus formed includes a water conduit therethrough which has a generally continuous axial bore for smooth flow therethrough of water in a high-velocity, high-volume propulsion stream.

The rotary-piston type of internal combustion engine is preferred for the power unit of the present propulsion unit primarily because of its simplicity and its inherently greater operating efficiency (presently about 1.6 horsepower per cubic inch displacement compared with about .7 horsepower per cubic inch displacement in reciprocating-piston type engines of non-special design). However, it should be understood that a reciprocating-piston type internal combustion engine may also be used in the marine propulsion unit of the present invention. In this embodiment, the conventional crankshaft is replaced by an impeller-output shaft having a generally axial bore therethrough which serves as the conduit for the propulsion stream of water, as previously described herein in connection with shaft 15. To preserve the generally smooth axial bore through the impeller-output shaft the eccentric cranks of the conventional crankshaft are replaced by eccentric cam lobes, as previously described herein in connection with cam lobes 19. Small eccentricities of such cam lobes are preferred for reciprocating-piston type engines to assure higher operating speeds (i.e., higher revolutions per minute). The conventional disc-like flywheel disposed at one end of the conventional crankshaft may thus also be eliminated and effectively replaced by the equivalent moment of inertia furnished by the mass of metal which forms the conduit walls of the impeller-output shaft and which is distributed over the length thereof at a large radius from the axis of rotation. Generally higher speed operation of the internal combustion engine enhances the operating efficiency of the impeller formed within the impeller-output shaft and may also reduce vibration and decrease the moment-of-inertia requirements of a flywheel. 7

However, where additional moment of inertia is required, a small, disc-like flywheel having an axial bore therethrough at least as large as the bore through the impeller-output shaft 15 may be attached thereto at the inlet or outlet end of the shaft 15. This incremental flywheel may operate in contact with the water flowing through the impeller-output shaft IS'and ideally may include inner flow-oriented vanes to enhance the propulsion operation of the impeller vanes 17. The flange region of either the inlet 11 or outlet 13 may be suitably recessed to receive such incremental flywheel.

In the embodiment of the present invention which uses a rotary-piston internal combustion engine, the impeller-output shaft 15 may alternatively be coupled to the rotary piston by means other than eccentric cam lobes 19. For example, the rotary piston may include an internal gear (located in substantially the same position as the outer race of bearing 59) which engages a grar of smaller diameter on the impeller-output shaft 15, as shown in FIG. 4". In this way, the impeller-output shaft 15 rotates at a higher angular velocity than the rotary piston, thereby increasing the effective moment of inertia and concomitant flywheel action provided by the impeller-output shaft, and also increasing the propulsion efficiency of the stages of impeller vanes 17.

Therefore, the marine propulsion unit of the present invention obviates the need for exposed rotating elements and associated shaft couplings, clutches, and the like. The internal conduit through the impeller-output shaft in accordance with the present invention combines the water-propulsion impeller and the requisite flywheel moment of inertia in a propulsion unit which is inherently simple, lightweight and safe, particularly for operation in boats used in water-contact sports.

I claim:

1. Liquid propulsion apparatus comprising:

an internal combustion engine including a chamber having an element movably disposed therein to form an expansible combustion chamber of said engine;

a rotatable shaft of said engine rotatably mounted therein and coupled to said element to rotate about a longitudinal axis in response to movement of said element within said chamber, said rotatable shaft having an internal bore therethrough substantially coaxially disposed with respect to said rotational axis along the length of said shaft between the ends thereof; and

at least one set of impeller vanes attached to said shaft within the internal bore between the ends thereof for imparting to a fluid within the bore a force along the rotational axis of the shaft directed toward one end thereof in response to rotation of said shaft.

2. Liquid propulsion apparatus as in claim 1 comprising an eccentric means disposed on said rotatable shaft and coupled to said element for moving said element within said chamber in response to rotation of said shaft, said eccentric means including a working surface which is located at a radius from the longitudinal axis of said shaft which is greater than the radius of said internal bore in the shaft at the location therealong of said eccentric means.

3. Liquid propulsion apparatus as in claim 1 wherein said rotatable shaft includes walls disposed about the internal bore therethrough which are impervious to propulsion liquid passing therethrough and which provide distributed moment of inertia over the length thereof to form the flywheel for the internal combustion engine.

4. Liquid propulsion apparatus as in claim 1 comprising:

bearings rotatably mounting said shaft in said engine;

and

an oil passage disposed within the walls of said shaft intermediate the outer surface thereof and the inside surface of the internal bore therethrough, said oil passage being everywhere eccentric the rotational axis of said shaft and communicating with said bearings and with said eccentric means.

5. Liquid propulsion apparatus as in claim 4 wherein:

said rotatable shaft comprises at least two longitudinal sections joined together along mating surfaces which include longitudinal portions;

at least one section including awall member having an outer surface and an inside surface which defines the internal bore through said shaft and including a portion of an eccentric means attached thereto; and

a recessed passage formed within a mating surface of at least one of a pair of shaft sections intermediate the outer and inside surfaces, said recessed passage forming said oil passage communicating with the working surface of the portion of eccentric means and with the outer surface of the wall member at a location along the length thereof near the position of a bearing thereon.

6. Liquid propulsion apparatus as in claim 1 comprising an auxiliary shaft rotatably mounted in said internal combustion engine in skew relationship to said rotatable shaft and coupled thereto intermediate the ends thereof for transferring rotational movement between said rotatable and auxiliary shafts.

7. Liquid propulsion apparatus as in claim 1 comprising:

inlet means having a liquid conduit therethrough and being attached to said internal combustion engine near one end of said rotatable shaft with the internal bore therethrough in liquid-communicating alignment with the liquid conduit of said inlet means; and

outlet means having a liquid conduit therethrough and being attached to said internal combustion engine near the opposite end of said rotatable shaft with the internal bore therethrough in substantial alignment with the initial portion of the liquid conduit of said outlet means.

8. Liquid propulsion apparatus as in claim 7 wherein:

said inlet means includes valve means for selectively terminating flow of liquid through the liquid conduit of said inlet means in the direction toward said internal combustion engine; and

said inlet means includes a liquid connection to the conduit of said inlet means at a location therealong on the side of said valve means remote from said internal combustion engine for supplying liquid to said engine for cooling the same substantially independently of the operating condition of said valve means.

9. Liquid propulsion apparatus as in claim 7 wherein:

said internal combustion engine includes an exhaust passage from said combustion chamber;

said outlet means includes an auxiliary passage which communicates with said exhaust passage of said engine near said opposite end of said rotatable shaft and which is eccentric the internal bore through said rotatable shaft in the initial portion of said outlet means; and

said outlet means includes mixing means along the liquid conduit therethrough which communicates with said auxiliary passage for combining fluids in said exhaust and auxiliary passages with liquid discharged from said opposite end of the rotatable shaft.

10. Liquid propulsion apparatus as in claim 9 comprising unidirectional valve means disposed within said auxiliary passage intermediate said mixing means and said engine for impeding flow of liquid toward said exhaust passage.

11. Liquid propulsion apparatus as in claim 7 comprising:

a boat including bottom and sides and stern and bow forming a hull, said hull including a water inlet aperture in the bottom thereof intermediate the bow and stem;

means for mounting said internal combustion engine within said hull with the rotatable shaft of said engine substantially aligned with the centerline from bow to stem of the hull and with said opposite end of said rotatable shaft near the stern of the hull;

said inlet means includes a water input port at the end of the liquid conduit therethrough remote from said engine;

means coupling said input port of said inlet means to the inlet aperture through the bottom of the hull for passing water therethrough; and

water discharge means including said outlet means coupled to said engine and having an outlet port disposed outside said hull for passing water discharged from said rotatable shaft generally rearwardly for propelling said boat.

12. Liquid propulsion apparatus as in claim 11 wherein said water discharge means includes selectively deflectable nozzle means coupled to said outlet means for directing the water discharge from said rotatable shaft in a selected direction to provide steerage and reverse maneuverability.

13. An impeller-output shaft for an internal combustion engine having movable piston means forming an expandable combustion chamber of said engine, and comprising: i

a rotatable shaft having an internal bore therethrough substantially coaxially disposed with respect to the rotational axis of the shaft along the length of the shaft between the ends thereof for conducting fluid through said shaft between the ends thereof;

a plurality of fluid-translating impeller vanes attached to the internal walls of said shaft and protruding radially inwardly therefrom; and

coupling means attached to said shaft for coupling to piston means radially oriented about said shaft for translating the radially-aligned movement of the piston means within the expandable combustion chamber into rotational motion of said shaft.

14. An impeller-output shaft as in claim 13 wherein said coupling means includes an eccentric cam lobe attached to the shaft for coupling to the movable piston means of the engine.

15. An impeller-output shaft as in claim 13 wherein the internal combustion engine is of the type including a rotary piston means having an internal gear, and said coupling means includes a gear on said shaft disposed to engage the internal gear in the rotary piston means of a rotary-piston internal combustion engine. 

1. Liquid propulsion apparatus comprising: an internal combustion engine including a chamber having an element movably disposed therein to form an expansible combustion chamber of Said engine; a rotatable shaft of said engine rotatably mounted therein and coupled to said element to rotate about a longitudinal axis in response to movement of said element within said chamber, said rotatable shaft having an internal bore therethrough substantially coaxially disposed with respect to said rotational axis along the length of said shaft between the ends thereof; and at least one set of impeller vanes attached to said shaft within the internal bore between the ends thereof for imparting to a fluid within the bore a force along the rotational axis of the shaft directed toward one end thereof in response to rotation of said shaft.
 2. Liquid propulsion apparatus as in claim 1 comprising an eccentric means disposed on said rotatable shaft and coupled to said element for moving said element within said chamber in response to rotation of said shaft, said eccentric means including a working surface which is located at a radius from the longitudinal axis of said shaft which is greater than the radius of said internal bore in the shaft at the location therealong of said eccentric means.
 3. Liquid propulsion apparatus as in claim 1 wherein said rotatable shaft includes walls disposed about the internal bore therethrough which are impervious to propulsion liquid passing therethrough and which provide distributed moment of inertia over the length thereof to form the flywheel for the internal combustion engine.
 4. Liquid propulsion apparatus as in claim 1 comprising: bearings rotatably mounting said shaft in said engine; and an oil passage disposed within the walls of said shaft intermediate the outer surface thereof and the inside surface of the internal bore therethrough, said oil passage being everywhere eccentric the rotational axis of said shaft and communicating with said bearings and with said eccentric means.
 5. Liquid propulsion apparatus as in claim 4 wherein: said rotatable shaft comprises at least two longitudinal sections joined together along mating surfaces which include longitudinal portions; at least one section including a wall member having an outer surface and an inside surface which defines the internal bore through said shaft and including a portion of an eccentric means attached thereto; and a recessed passage formed within a mating surface of at least one of a pair of shaft sections intermediate the outer and inside surfaces, said recessed passage forming said oil passage communicating with the working surface of the portion of eccentric means and with the outer surface of the wall member at a location along the length thereof near the position of a bearing thereon.
 6. Liquid propulsion apparatus as in claim 1 comprising an auxiliary shaft rotatably mounted in said internal combustion engine in skew relationship to said rotatable shaft and coupled thereto intermediate the ends thereof for transferring rotational movement between said rotatable and auxiliary shafts.
 7. Liquid propulsion apparatus as in claim 1 comprising: inlet means having a liquid conduit therethrough and being attached to said internal combustion engine near one end of said rotatable shaft with the internal bore therethrough in liquid-communicating alignment with the liquid conduit of said inlet means; and outlet means having a liquid conduit therethrough and being attached to said internal combustion engine near the opposite end of said rotatable shaft with the internal bore therethrough in substantial alignment with the initial portion of the liquid conduit of said outlet means.
 8. Liquid propulsion apparatus as in claim 7 wherein: said inlet means includes valve means for selectively terminating flow of liquid through the liquid conduit of said inlet means in the direction toward said internal combustion engine; and said inlet means includes a liquid connection to the conduit of said inlet means at a location therealong on the side of said valve means remote from said internal combustion engine for supplying Liquid to said engine for cooling the same substantially independently of the operating condition of said valve means.
 9. Liquid propulsion apparatus as in claim 7 wherein: said internal combustion engine includes an exhaust passage from said combustion chamber; said outlet means includes an auxiliary passage which communicates with said exhaust passage of said engine near said opposite end of said rotatable shaft and which is eccentric the internal bore through said rotatable shaft in the initial portion of said outlet means; and said outlet means includes mixing means along the liquid conduit therethrough which communicates with said auxiliary passage for combining fluids in said exhaust and auxiliary passages with liquid discharged from said opposite end of the rotatable shaft.
 10. Liquid propulsion apparatus as in claim 9 comprising unidirectional valve means disposed within said auxiliary passage intermediate said mixing means and said engine for impeding flow of liquid toward said exhaust passage.
 11. Liquid propulsion apparatus as in claim 7 comprising: a boat including bottom and sides and stern and bow forming a hull, said hull including a water inlet aperture in the bottom thereof intermediate the bow and stern; means for mounting said internal combustion engine within said hull with the rotatable shaft of said engine substantially aligned with the centerline from bow to stern of the hull and with said opposite end of said rotatable shaft near the stern of the hull; said inlet means includes a water input port at the end of the liquid conduit therethrough remote from said engine; means coupling said input port of said inlet means to the inlet aperture through the bottom of the hull for passing water therethrough; and water discharge means including said outlet means coupled to said engine and having an outlet port disposed outside said hull for passing water discharged from said rotatable shaft generally rearwardly for propelling said boat.
 12. Liquid propulsion apparatus as in claim 11 wherein said water discharge means includes selectively deflectable nozzle means coupled to said outlet means for directing the water discharge from said rotatable shaft in a selected direction to provide steerage and reverse maneuverability.
 13. An impeller-output shaft for an internal combustion engine having movable piston means forming an expandable combustion chamber of said engine, and comprising: a rotatable shaft having an internal bore therethrough substantially coaxially disposed with respect to the rotational axis of the shaft along the length of the shaft between the ends thereof for conducting fluid through said shaft between the ends thereof; a plurality of fluid-translating impeller vanes attached to the internal walls of said shaft and protruding radially inwardly therefrom; and coupling means attached to said shaft for coupling to piston means radially oriented about said shaft for translating the radially-aligned movement of the piston means within the expandable combustion chamber into rotational motion of said shaft.
 14. An impeller-output shaft as in claim 13 wherein said coupling means includes an eccentric cam lobe attached to the shaft for coupling to the movable piston means of the engine.
 15. An impeller-output shaft as in claim 13 wherein the internal combustion engine is of the type including a rotary piston means having an internal gear, and said coupling means includes a gear on said shaft disposed to engage the internal gear in the rotary piston means of a rotary-piston internal combustion engine. 